Rheostat.



M. L. SEVERY a G. B. slNcLAm.

RHEGSTAT.

APPLICATION FILED DEC`22. |914.

1,236,772. Patented Aug. 14, 1917.

UNITED STATES PATENT oEErcE.

MELVIN L. SEVERY, OF ARLINGTON HEIGHTS, MASSACHUSETTS, AND GEORGE B. SINCLAIB., 0F GEORGETOWN, MAINE.

,RHEOSTA'L Original application led February 25, 1910, Serial No. 545,963.

Speccation of Letters Patent.

22, 1914. Serial No. 878,471.

To all whom 'it may concern:

Be it known that We, MELVIN L. SEVEEY and Gfx-:ones B. SINoLAm, citizens of the United States, residing, respectively, at Arlington Heights, in the county of Middlesex and State of 'Massachusetts and at Georffetown, in the county of Sagadahoc and `tate of Maine, have invented certain new and useful Improvements in Rheostats, of which the following is a specification.

The present application is a division of an application, Serial No. 545,963, led in our joint names on the 25th day of February, 1910, which eventuated in Letters Patent No. 1,125,746, dated January 19, 1915. It is designed to cover separately and in detail the rheostat or resistance device set forth in the parent application as a part of the complete structure.- This divisional application is filed pursuant to official requirement.

In the' accompanying drawings:

Figurel is across section of our rheostat;

Fig. 2 is a perspective view of one of the elements of th`e` rheostat;

Fig. 3 is a perspective view of a coupled pair of said elements, but with thewiring thereof not shown;

Fig. 4 is a erspective view of the rheostat box and brus carrier with the intermediate sect-ion of the same broken away; an

Fig. 5 is an enlarged edge view of an element showin alead therefrom.

Each of the r eostat elements consists of a thin rectangular plate of insulating material 1, havin wound thereon a multiplicity of turns of ne-wire 2. This wire is pre erably bare, but is wound so perfectly parallel as not to allow contact etween any of its Several coils or turns.. the late 1, several of the windings or coils,

re erably five, are prolonged into extension oops 3 and twisted more or less at such edge (as in Fig. 5) in order to retain such coils in place. These extension loops 3 are to serve as lead wires by which the current can be cut 'into the resistance wire 2 at different points, and so vary the length thereof in a circuit. A lead wire 4 being joined to the wire 2 at the extreme left han end, asshown in Figs. 1 and 2, the circuit between the right-hand loop 3 and said wire 4 will comprise all the turns o f the wire 2, while the circuits between the intermediate loops 3 and said wire 4 will embrace At one edge of Figs. 1 and fewer turns, and consequently have less re-` sistance therein.

After the plate 1 Vhas been wound as above set forth, with the loops 3 and lead 4 projecting therefrom, :i suitable insulatin Inaterial preferably in liquid form, as s ellac or other varnish, is laid over the wires 2,

either by means of a brush, by dipping the edge of which is curved concentric with a point just beyond the opposite ends of the elements l; and to this curved edge or face are fastened several contacts 9 equal in number to the sum of the loops 3 on the two elements 1. In the lateral face of this cross piece are formed rooves 1() into which, the lead wire 4 and oops 3 are laid, each of them being suitably secured, rcferably by solder, to a contact 9; the leas 4 and loops 3 of one element lying in grooves 10 at one side of the cross piece, and tlielead and loops of the other element lying in the grooves at the opposite side.

In the top and4 bottom `of the elongated box 11 are numerous transverse grooves 12 into which the coupled elements can be slid, the thin .bars 5 fitting said grooves and a longitudinal strip 13 limiting the distance to which said coupled elements 0, as shown in Fig. 1. At the back of thisbbox is rotatably supported a longitudinal shaft 14, as in the curved faces of the cross pieces 7; and upon the ends of said shaft are fixed the arms 15 carrying at their free ends a bar 16, preferably. of angle-iron, to the outer face of which issccured an insulating strip 17, preferably wood, carrying the brushes 18 whose extremities sweep the said contacts 9 as said shaft is rocked, there being one brush for each resistance unit. The brush-carrying members are moved by means of gravity an a tension spring 19 and link 20 extending to any suitable operating means, different 4, substantially concentric with groups of wires being successively added to or removed from the line 0r circuit as the brushwarrying member thus shifted.

In thcdrawings we lun'e shown the groups of coils varying in the number of turnsor windings which they respectively include.- This inaylpr may not be followed in practice, according as'the rheostat is to be applied to one or another specific usc. The unequal spacing here shown is particuuarly intended for electrical musical instruments, and is set out in detail in the parentapplication, but not being claimed in thisy divisional application need lnot be further referred to herein. It will be observed that each contact brusli'l 'sweeps its own set of contacts 9, and `cuts into or out of circuit the windings or coils of its own resistance unit only. By introducingeach resistance-unit into a circuit or branch circuit individual to itself, the rheostat is adapted t0 control' simultaneously and through movement of a single actuating member, as many circuits or branch circuits as there are resistance units and contact brushes. So, too, individual resistance units can be added, withdrawn, or replaced by others of different winding, as circumstances may require. The primary field of use of the rheostat here set forth is in connection with electrically-actuated musical instrumentgto vary-the attracting .power of the'electromagnets thereof, but -it` 1s obviously capable of use in numerous other relations.

Having thus described our inventioin'what- LA rheostat comprising a box trans verscly grooved in its top and bottom members; a plurality of plates slidably carried in said grooves, each plate having wound a multiplicity of turns of Wire Suitthereon ably insulated from each other, each .plate having connected therewith a pluralit ofcontacts wired to diferent sections o turns, all said contacts being in. the same curved surface; a'member pivoted to move concentric with said surface; and brushes its . ing material fastened to said bars,

vthe plates, each plate bers; removable resistance elements therefor case of two thin hars fitconsisting' in each ting said grooves, two fiat plates fastened at their ed es to said bars, each plate having wound t ereon a multiplicity of turns of wire, an externally curved member fixed to the ends of said bars, contacts affixed to the curved surface of said member, leads between sa-id contacts and different sections of said turns, and a movable member carrying brushes sweeping said contacts.

3. A rheostat element comprising two thin bars; two rectangular plates of insulatthe edges of the latter projecting beyond the edges of being wound with a multiplicity of non-contacting turns of wire; a cross piece terminally. fastened to the ends of said bars and having transverse grooves in its lateral faces; contact blocks axed to its outer face;'and leads attached Ato said contacts and Pasingr through said grooves to 'dierent-sections of said turns cf wire.

4. A rheostat comprising a supporting member, a plurality of resistance umts car- Em F. DUNLOP, Enwmm S. Caoaxm'r.

said armsxand brushes carried by 

